export default (function (o, c, d) {
  var LT = 'h:mm A'
  var L = 'MM/DD/YYYY'
  var calendarFormat = {
    lastDay: '[Yesterday at] ' + LT,
    sameDay: '[Today at] ' + LT,
    nextDay: '[Tomorrow at] ' + LT,
    nextWeek: 'dddd [at] ' + LT,
    lastWeek: '[Last] dddd [at] ' + LT,
    sameElse: L,
  }
  var proto = c.prototype

  proto.calendar = function (referenceTime, formats) {
    var format = formats || this.$locale().calendar || calendarFormat
    var referenceStartOfDay = d(referenceTime || undefined).startOf('d')
    var diff = this.diff(referenceStartOfDay, 'd', true)
    var sameElse = 'sameElse'
    /* eslint-disable no-nested-ternary */

    var retVal =
      diff < -6
        ? sameElse
        : diff < -1
        ? 'lastWeek'
        : diff < 0
        ? 'lastDay'
        : diff < 1
        ? 'sameDay'
        : diff < 2
        ? 'nextDay'
        : diff < 7
        ? 'nextWeek'
        : sameElse
    /* eslint-enable no-nested-ternary */

    var currentFormat = format[retVal] || calendarFormat[retVal]

    if (typeof currentFormat === 'function') {
      return currentFormat.call(this, d())
    }

    return this.format(currentFormat)
  }
})
